L. A. Mitscher

The conformation of erythronolide, the 14-membered aglycone ring of the erythromycin antibiotics☆

Abstract The solution conformation of erythronolide B and derivatives has been deduced from NMR and CD spectral data. The conformation is basically a “diamond lattice” type in which the ring atoms occupy cyclohexane-like positions but slightly modified to incorporate the lactone and ketone groups and to relieve an unfavorable syn -periplanar interaction. Variable temperature experiments revealed that erythronolide B and derivatives do not undergo facile ring inversion or pseudorotation and suggested the presence of a single stable conformation. Several features of the proposed conformation were demonstrated by the NMR and CD spectra of suitable derivatives. These features included the syn -periplanar relationship between the 3- and 5-OH groups, the axial orientation of the 11-OH group, and the proximity of the 6-OH group to the 9-ketone.

Chemical ionization mass spectra of macrolide antibiotics

Chemical ionization mass spectrometry is shown to be a valuable tool for structural analysis of certain macrolide antibiotics.

Fragmentation process occurring in proton-transfer chemical-ionization mass spectrometry

The isobutane chemical-ionization mass spectra of deuterium-labelled model compounds show that fragmentation can occur at locations remote from the site of protonation.